Really? You can tell off the top of your head what the difference between an xvalue and a glvalue is? Which function has higher precedence in the overload list out of foo(string&) and foo(string&&)? (Note that's not a const string&!) That these are so obvious to you that there's no chance you would make a mistake about them when you're in a hurry trying to solve an actual problem that has its own complexities rather than playing games with C++'s unnecessary complexity? The one where foo(std::move(x)) doesn't necessarily move x is a particular killer (although at least it only causes a performance problem rather than noticable change in behaviour).

I have worked with C++ for a hell of a lot more than 2 hours since C++11 came out (the first version with move semantics) and worked with many others that have too, and I can tell you that "once you have it you're done" is just not true. I fully understand all the concepts but I can still make mistakes.